1. Field of the Invention
The present invention generally relates to the design and documentation of complex electronically interconnected systems and, more particularly, to automation of the drawing of schematic diagrams depicting interconnections of elements of the system through wiring, busses and cables and production of other diagrams and documentation correlated to such drawings.
2. Description of the Prior Art
Increasing computational and data processing power of modern digital circuits has allowed the design and fabrication of systems and devices of extremely high performance which were impossible only a few years ago due to the impracticality of exploiting that potential performance. For example, the performance of aircraft has been greatly increased by exploitation of instabilities which could not previously be controlled by a human pilot but can be managed by the ability of modern data processors to rapidly collect and assimilate large amounts of information from various types of sensors and to manipulate portions of the aircraft to achieve control functions consistent with control commands manually input by the pilot. Thus the pilot can control the aircraft in the same manner as controlling an aircraft not subject to such instabilities while largely unaware of the actual manipulations of the portions of the aircraft. Such complex systems for aircraft control and other purposes are broadly referred to as avionics. As another example, the integration of sub-systems to improve and coordinate overall function, such as in environmental and operational controls of a large vehicle, building, assembly line, manufacturing plant, multi-site network or the like, may result in a system too complex to be managed or maintained by a sufficiently small number of people to be operationally or economically feasible. Nevertheless, such complex systems may be managed by suitable control processors and often more efficiently and effectively than a large number of human operators.
The design of complex systems and devices also imposes physical constraints on the overall design. For example, particularly in avionics applications, the system will be comprised of many functional units distributed throughout the aircraft as dictated by space, weight and other design constraints. Such distribution of the complex system requires numerous cables and/or wiring yokes containing a few to several thousand individual connections or more used to connect the functional units. Formation of connections by cables and wiring yokes is often necessary in vehicles such as automobiles or aircraft which are subject to vibration since the mutual support of the connections and the further support and protection of cabling structures significantly reduces the potential for damage to individual connections and increases reliability.
Cables must often be designed for specific applications and interconnections to be made since, for example, unused connections should generally be avoided to reduce weight, capacitive or inductive coupling and the like. The signals or power carried by the connections must also be considered in such designs to specify the types of connections made such as wire gauge, twisted pair or group wiring, ribbon cable, order of connector pins at cable terminations, shielding and the like. Compatibility of connectors and pin assignments therein must often be coordinated between numerous suppliers and consistency must be maintained.
While software is known which can automate specification of point-to-point connectivity in complex system designs, at the present state of the art, design of cabling must be done manually. Specifically, even using computer assisted design (CAD) arrangements to produce graphic representations of the cable designs, time-consuming manual transposition of point-to-point connectivity data was required and resulted in inconsistencies of design style in the finished product when numerous draftsmen work on particular ones of the numerous sheets of drawings generally required.
Such manual intervention is understandably error-prone and prevents automated error detection or automated design revision to implement changes which may be necessitated by other manually input changes to the design. Likewise, logging of design changes becomes difficult since the documentation is, at best, in the form of full drawings and particular changes are not specifically identified. Further, for the same reason, the form of data resulting from the CAD operation is not in a form from which manufacturing data, such as parts lists, cable lengths, connector types and the like can be extracted other than manually. The time required for revisions necessitated by design changes and error correction also delays and complicates system testing and integration since changes in system connectivity require extended turn-around time for inclusion in drawings and other documentation.
These difficulties remain even after the system or device is produced since schematic diagrams must be provided to permit repair and maintenance of the system or device. Block diagrams at various levels of abstraction, such as assembly drawings and illustration of system operational hierarchy or architecture as well as indices for service or assembly manuals are generally prepared manually from the schematic diagrams for reference documentation of the system and the intervention by data entry personnel is again error-prone and may obscure the hierarchical architecture or the configuration control properties of the system.
In connections with these concerns described above, drawings of large and complex systems must be partitioned in order to develop legible renderings on each of perhaps a very large number of sheets. At the same time, for reference of systems integrators and maintenance and repair personnel, this partitioning must also allow rapid assimilation and congruence with physical layout of the system and thus must embody a logical grouping on each sheet. Such a logical grouping consistent with practical limitations on graphical content is very difficult to organize, particularly for manual rendering or manual transposition for CAD rendering. At the same time, development of indices or other listings in accordance with drawing content becomes exceptionally difficult to track as systems become large and the number of sheets of drawings increases.
This difficulty can be readily understood since CAD files, for example, are developed with reference to a drawing sheet and do not provide for tracking of content, as alluded to above. Likewise, from the standpoint of connectivity information, there has been no mechanism or methodology for systematically approaching layout of a schematic depiction on a page or addressing the issue of accommodating operational function and/or logical grouping during drawing layout. As complex systems become large, these issues become more complex than can be comprehensively organized by the number of people required to transpose connectivity data to CAD files and the likelihood of errors and, particularly, omissions, is dramatically increased.